2008 KV42, nicknamed Drac (short for Dracula), is a trans-Neptunian object orbiting the Sun in retrograde motion (backwards) and almost perpendicular to the ecliptic: it has a 104-degree inclination. This odd orbit suggests that 2008 KV42 may have been perturbed inwards from the Oort cloud. Comets are thought to originate from the Oort cloud and this discovery may finally show how they transition from the Oort cloud to become objects like Halley's Comet. 2008 KV42 is only 1 of 5 objects known to have i>60 and q>15AU (HiHq objects).
The orbits of trans-Neptunian objects provide important clues as to how the outer Solar System took form and evolved. Discoveries of new classes of objects have led to fresh insights into the early history of the Solar System, challenging accepted theories. The discovery of 2008 KV42, the first-ever object in this region to be detected with a retrograde orbit, promises to do just that.
"Although we've been specifically looking for highly-tilted trans-Neptunians for some time now, we didn't expect to find a retrograde one", said Dr. JJ Kavelaars of the National Research Council of Canada. "A number of theories on the formation of the outer Solar System have suggested that such things might be out there, but observational searches for them are very difficult."
Part of the difficulty is that these objects are extremely rare. Despite having surveyed most of the northern sky for bright objects of this type, astronomers have found only one other that might belong to the same class as 2008 KV42. Discovered in 2002 by the Deep Ecliptic Survey, (127546) 2002 XU93 has an orbit on a 77-degree tilt.
One of the great frustrations for researchers looking into the region beyond Neptune has been trying to pin down the source regions for various comet types. Finding objects that provide a link between the source region and the observed comet population is an enormous help in choosing between the source regions, greatly clarifying our understanding of the formation of the outer Solar System.
This discovery was made using the Canada–France–Hawaii Telescope in Hawaii, with follow-up observations provided by the MMT telescope in Arizona, the Cerro Tololo Inter-American Observatory (CTIO) 4-metre telescope in Chile, and the Gemini South telescope, also in Chile, of Canada's Gemini Observatory. The discovery team consists of scientists in Canada, France, and the United States.
"Having quick access to the MMT and Gemini South telescopes, via the generous support of the observers at MMT and the Canadian Director of Gemini South, Jean‑René Roy, was a huge help here. Given the highly unusual orbit, the object would have been lost without the critical tracking contribution of these large telescopes," said Dr. Brett Gladman, an astronomy professor and Canada Research Chair at the University of British Columbia.
The discovery team is currently planning follow-up observations of 2008 KV42 to pin down its orbit with greater precision. The work of unraveling the archaeological information trapped in the orbit of this trans-Neptunian object can then begin.
The discovery of 2008 KV42 was announced at the 10th triennial "Asteroids, Comets and Meteors" meeting in Baltimore and via the Minor Planet Electronic Circular (MPEC) 2008-O02 on July 16, 2008, and International Astronomical Union electronic circular (IAUC) 8960 on July 18, 2008. Recent observations taken with the Canada-France-Hawaii Telescope have further refined our knowledge of the orbit, securing this as a possible link between the inner Oort cloud and the Halley-type comets.
With a semi-major axis of 46±5 AU, 2008 KV42 was discovered while at a distance of 32 AU and has a perihelion at roughly the distance of Uranus.